The role played by the chick liver estrogen receptor in the regulation of hepatic biosynthetic events induced by the administration of the hormone will be studied. Attempts will be made to physically and biochemically characterize the nuclear form of the receptor. This will be performed by developing techniques for the subnuclear localization of the receptor and its subsequent characterization by physical techniques including gel chromatography, sucrose gradient centrifugation and electrophoresis. Subsequent to solubilization and characterization, the purification of sufficient quantities of receptor for use in biochemical studies will be attempted. Such an approach should lead to a clearer understanding of the role of the estrogen receptor in regulation of biosynthetic events.